Telephone substation circuits



'W. H. EDWARDS TELEPHONE SUBSTATION CIRCUITS Feb. 2 1926.

Filed Dec. 24, 1923 W ATTORNEY Patented Feb. 2, 1926.

UNITED STATES WILLIAM H. EDWARDS, OF BROOKLYN, NEW YORK, ASSIGNOR TOAMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

TELEPHONE SUBSTATION CIRCUITS.

Application filed December 24, 1923. Serial No. 682,529.

To all whom it nmg concern:

Be it known that I, TVIL'LIAM H. En wninns, residing at Brooklyn, in thecounty oi Kings and State of New York, have invented certainIIIJPL'OVGIHQIltS in Telephone Substation Circuits, of which thefollowing is a specification.

' This invention relates to telephone sub station sets, and moreparticularly to cableincns testing sets which are suitable for use inmachine switching central oliice districts The principal object oi. theinvention is to provide means by which a cable splicor may (1) monitoron a cable pair to determine whether it is in use or not, (2) talk,listen and. dial, and receive calls from a central otiice.

Applicants lDVQHt'lOn provides tor a circuit arrangement which givescommon battery signaling and local battery talking. A. three-positionswitching means'is provided, which in the normal position permits ofmonitoring on a cable pair, in the secend position permits of talking,listening and dialing, and. in the third position connects analternating current annunciator in series with a condenser across theline, for the purpose of receiving calls from the central. ofi'ice.

The circuit arrangement will be more clearly understood when thefollowing dctailed description of the preferred form is read withreference to the accon'ipanying drawing, which shows diagramn'iaticallysuch arrangement.

The apparatus indicated in the circuit diagram includes the receiver 1,the transmitter 2, the local battery 8, an induction coil, thealternating current ringer 4:, the condenser 5, the condenser 6, adialing arrangement labeled Dial, and a three-position key. The threepositions of this key are labeled M, T, and \V. The position M is themonitoring position; the position T is the talking, listening, anddialing positon; and the position 7 is the position used when thecableman wishes to wait for a call from the central otfice. A and B arethe cord wires which may be connected to the cable pair selected. Theplug and jack c011- nections are indicated on the drawing.

Viith the key in the normal or M position, the receiver is connectedacross the line, and the transmitter is cut out. The operative circuitis as follows: A, condenser 5, closed contact 7, receiver 1, and B.

With the key in the second position, contacts are closed at 8 and 9, andwhen the cableman dials, contact is closed at 10. The receiver circuitis the same as that in the case of the first position of the key. Thetransmitter circuit is closed as follows: transmitter 2, contact 9, andbattery 3. The dialing circuit is: A, contact 7, contact 10, and B.

In the third position of the key, contact is made at 11 (and, of course,contacts 8 and 9 are broken) and the alternating current ringer 4t andthe condenser 6 are. conneeted in series across the line. The circuit isas follows: A, contact 11, ringer 4, condenser 6, and B.

hat is claimed is:

A telephone substation set including a transmitter, a local batterytherefor, a re ceiver, a condenser, an induction coil, an alternatingcurrent annuneiator, a second condenser associated therewith, a dialingarrangement, and a three-positionswitching means, which switching meansin the first posit-ion connects the receiver and the first condenseracross the line and cuts out the transmitter; in the second positionconnects the receiver and the first condenser across the line, closes acircuit including the trans mitter and the local battery, and prepares adialing circuit; and in the third position connects across the line thealternating cur rent annunciator and the second condenser.

In testimony whereof, I have signed my name to this specification this21st day of December, 1923. 1

VILLIAM H. EDWARDS,

